tools/metrics/histograms/metadata/variations/histograms.xml

<!--
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Use of this source code is governed by a BSD-style license that can be
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<!--
This file is used to generate a comprehensive list of Variations histograms
along with a detailed description for each histogram.

For best practices on writing histogram descriptions, see
https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/histograms/README.md

Please follow the instructions in the OWNERS file in this directory to find a
reviewer. If no OWNERS file exists, please consider signing up at
go/reviewing-metrics (Googlers only), as all subdirectories are expected to
have an OWNERS file. As a last resort you can send the CL to
chromium-metrics-reviews@google.com.
-->

<histogram-configuration>

<histograms>

<histogram name="Variations.AppliedSeed.Size" units="bytes"
    expires_after="2022-11-20">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The size of the variations seed (serialized uncompressed proto) that is
    loaded on startup and used. Note that not all loaded seeds are used; for
    example, expired seeds are not used. The seed could be a regular seed or a
    safe seed. Recorded after setting up field trials with the seed.
  </summary>
</histogram>

<histogram name="Variations.AppliedSeed.StudyCount" units="studies"
    expires_after="2022-11-20">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The number of studies contained in the seed that is being used. Note that
    the client may not participate in all studies due to study filtering. The
    seed could be a regular seed or a safe seed. Recorded before setting up
    field trials with the seed.
  </summary>
</histogram>

<histogram name="Variations.AppSeedFreshness" units="minutes"
    expires_after="2022-06-19">
  <owner>rmcelrath@chromium.org</owner>
  <owner>ntfschr@chromium.org</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    The time interval between when a WebView-using app's copy of the variations
    seed was written to its local app storage and when it was loaded for use.
    This is different from Variations.SeedFreshness because it measures
    freshness from when the app received its copy of the seed, not when the seed
    was originally downloaded. Written every time the browser process
    initializes, but not if there was an error reading the seed, or no seed
    existed.
  </summary>
</histogram>

<histogram name="Variations.AppSeedRequestState" enum="AppSeedRequestState"
    expires_after="2020-11-01">
  <obsolete>
    Removed from code October 2020.
  </obsolete>
  <owner>rmcelrath@chromium.org</owner>
  <owner>ntfschr@chromium.org</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    The result of checking if a WebView-using app's copy of the variations seed
    is still fresh, or if a new seed should be requested.
  </summary>
</histogram>

<histogram name="Variations.ExtendedSafeMode.BeaconFileDeserializationError"
    enum="JsonDeserializationError" expires_after="2022-06-05">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics&gt;Variations</component>
  <summary>
    The error code given by JSONFileValueDeserializer::Deserialize(). Emitted
    during CleanExitBeacon initialization when the beacon file cannot be
    deserialized. In other words, it is emitted whenever the &quot;Not
    deserializable&quot; bucket of the BeaconFileStateAtStartup histogram is
    emitted. Note that this file is used by only one branch of the Extended
    Variations Safe Mode experiment.
  </summary>
</histogram>

<histogram name="Variations.ExtendedSafeMode.BeaconFileStateAtStartup"
    enum="BeaconFileState" expires_after="2022-06-05">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics&gt;Variations</component>
  <summary>
    The state of the beacon file and its contents, e.g. readable or not
    deserializable. See the BeaconFileDeserializationError histogram for more
    details on why the file was not deserializable. Note that this file is used
    by only one branch of the Extended Variations Safe Mode experiment. Recorded
    when the CleanExitBeacon is initialized.
  </summary>
</histogram>

<histogram name="Variations.ExtendedSafeMode.BeaconFileWrite"
    enum="BooleanSuccess" expires_after="2022-06-05">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics&gt;Variations</component>
  <summary>
    Denotes whether the beacon file was successfully written. Note that this
    file is used by only one branch of the Extended Variations Safe Mode
    experiment. Recorded immediately after Chrome tries to write the file.
  </summary>
</histogram>

<histogram name="Variations.ExtendedSafeMode.GotVariationsFileContents"
    enum="BooleanSuccess" expires_after="2022-06-05">
  <obsolete>
    Replaced with Variations.ExtendedSafeMode.BeaconFileState in M99.
  </obsolete>
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics&gt;Variations</component>
  <summary>
    Whether getting file contents from the Variations beacon file succeeded.
    This is the case when the file exists, its contents are successfully read,
    and its contents are non-empty and in the expected format. Note that this
    file is used by only one branch of the Extended Variations Safe Mode
    experiment. Recorded when the CleanExitBeacon is initialized.
  </summary>
</histogram>

<histogram name="Variations.ExtendedSafeMode.WritePrefsTime"
    units="microseconds" expires_after="2022-06-05">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics&gt;Variations</component>
  <summary>
    The time it takes to write prefs to disk. The time is capped at 1s. The
    metric is emitted before field trials are set up. Only clients on non-stable
    channels in the ExtendedVariationsSafeMode experiment's WritePrefs and
    SignalEarlyAndWritePrefs groups emit the metric.

    Note that clients without high-resolution clocks will report 0 for very
    short times.
  </summary>
</histogram>

<histogram name="Variations.FirstRun.SeedConnectTime" units="ms"
    expires_after="2022-04-22">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The latency of connection to the variations server when fetching an initial
    variations seed during Android Chrome first run. This is included in the
    Variations.FirstRun.SeedFetchTime measurement. Only considers cases where an
    HTTP 200 result was received.
  </summary>
</histogram>

<histogram name="Variations.FirstRun.SeedFetchResult"
    enum="VariationsSeedFetchResult" expires_after="2022-04-22">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of attempting to fetch an initial variations seed during Android
    Chrome first run. Records both the HTTP code and various error values in one
    enumeration. Prior to M95, non-200 HTTP codes were counted as IOException.
    Starting with M95, these codes are logged separately.
  </summary>
</histogram>

<histogram name="Variations.FirstRun.SeedFetchTime" units="ms"
    expires_after="2022-06-26">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The latency of fetching an initial variations seed during Android Chrome
    first run. Only considers cases where an HTTP 200 result was received.
  </summary>
</histogram>

<histogram name="Variations.FirstRunPrefsDebug"
    enum="VariationsFirstRunPrefEvents" expires_after="2021-08-29">
  <obsolete>
    Removed 2021/08.
  </obsolete>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Logs each event related to Android Chrome variations first run prefs to
    debug crbug.com/1090968.
  </summary>
</histogram>

<histogram name="Variations.FirstRunResult" enum="VariationsFirstRunResult"
    expires_after="2022-06-14">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of attempting to import an initial variations seed during Android
    Chrome first run. Logged from VariationsSeedStore::LoadSeed when seed prefs
    do not exist.
  </summary>
</histogram>

<histogram name="Variations.Headers.DomainOwner" enum="VariationsHeadersOwner"
    expires_after="2022-04-24">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics</component>
  <summary>
    The owner of the top-level domain from which certain subframe-initiated HTTP
    requests are made. It's logged after determining that (i) the request should
    include variations headers, (ii) the request is from a subframe, and (iii)
    TrustedParams are not present. It's logged before adding headers. It allows
    us to verify whether non-render-thread-initiated requests, if any, lack
    TrustedParams.
  </summary>
</histogram>

<histogram name="Variations.Headers.ExperimentCount" units="units"
    expires_after="2022-07-03">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records number of experiment ids in the X-Client-Data header at the time the
    header is constructed.
  </summary>
</histogram>

<histogram name="Variations.Headers.RequestContextCategory"
    enum="VariationsHeadersRequestContextCategory" expires_after="2022-04-24">
  <owner>asvitkine@chromium.org</owner>
  <owner>jwd@chromium.org</owner>
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <component>Internals&gt;Metrics</component>
  <summary>
    Details about the request context in which an HTTP request is made. Logged
    after determining that the request should include variations headers but
    before adding the headers.
  </summary>
</histogram>

<histogram
    name="Variations.Headers.URLValidationResult{VariationsHeadersURLValidationResult}"
    enum="VariationsHeadersURLValidationResult" expires_after="2022-03-15">
  <owner>asvitkine@chromium.org</owner>
  <owner>jwd@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of whether to append Variations headers to a request. Logged when
    when determining (i) whether the URL to which the request is being sent
    should have a variations header and (ii) whether--after a redirect--the
    request to which a variations header was added should have the variations
    header removed. {VariationsHeadersURLValidationResult}
  </summary>
  <token key="VariationsHeadersURLValidationResult">
    <variant name="">
      <obsolete>
        Base histogram. Use suffixes of this histogram instead.
      </obsolete>
    </variant>
    <variant name=".Append"
        summary="Result when checking whether to append a header."/>
    <variant name=".Remove"
        summary="Result when checking whether to remove a header."/>
  </token>
</histogram>

<histogram name="Variations.InvalidStudyReason"
    enum="VariationsInvalidStudyReason" expires_after="2022-02-26">
  <owner>jwd@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the reason for rejecting an invalid study. Recorded when processing
    the variations seed at startup and when simulating a new seed.
  </summary>
</histogram>

<histogram name="Variations.LoadPermanentConsistencyCountryResult"
    enum="VariationsPermanentConsistencyCountryResult"
    expires_after="2022-04-22">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records how the country code saved in prefs used for filtering permanent
    consistency studies compares to the country code in the variations seed.
    This is recorded each time the saved country code is loaded from the pref.
  </summary>
</histogram>

<histogram name="Variations.LoadSeedSignature" enum="VariationSeedSignature"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of verifying the latest variations seed's signature, recorded
    when the seed is loaded from Local State. Not recorded when running in safe
    mode.
  </summary>
</histogram>

<histogram name="Variations.PolicyRestriction"
    enum="VariationsRestrictionPolicyValues" expires_after="2022-04-30">
  <owner>pastarmovj@chromium.org</owner>
  <owner>ydago@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the restrictions on how experiment variations are applied on the
    client. This is recorded at start up.
  </summary>
</histogram>

<histogram name="Variations.RequestCount" units="units"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Number of previous requests to the variations server in the same session,
    logged each time a new request is attempted to the variations server. For
    example, the value of the 0th bucket indicates the number of initial
    requests to the server that took place.
  </summary>
</histogram>

<histogram name="Variations.ResourceRequestsAllowed"
    enum="VariationsResourceRequestsAllowedState" expires_after="2022-06-14">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Counts the number of times the VariationsService is allowed or not allowed
    to make a request due to the ResourceRequestAllowedNotifier. Useful for
    debugging cases where variations seeds may not be getting fetched.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.FellBackToSafeMode2"
    enum="BooleanSafeMode" expires_after="2021-08-29">
  <obsolete>
    Replaced by Variations.SeedUsage in September 2021, M95.
  </obsolete>
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Whether or not the VariationsService fell back to safe mode due to too many
    crashes or failed seed fetches. Recorded during Chrome startup immediately
    before field trials are created. Only recorded if either a recent seed or a
    safe seed was loaded successfully.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.LoadSafeSeed.Result"
    enum="VariationsSeedLoadResult" expires_after="2022-06-14">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records whether the safe variations seed was successfully read from disk on
    startup. Records a detailed reason on read failure. Only recorded when
    attempting to run in safe mode.

    Expired after M77 and revived in M93.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.LoadSafeSeed.SignatureValidity"
    enum="VariationSeedSignature" expires_after="2022-06-14">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of verifying the safe variations seed's signature. Recorded when
    the seed is loaded from disk. Only recorded when attempting to run in safe
    mode.

    Expired after M77 and revived in M93.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.StoreSafeSeed.Result"
    enum="VariationsSeedStoreResult" expires_after="2022-06-14">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the result of attempting to store a safe variations seed (and all
    associated metadata) on disk.

    Expired after M77 and revived in M93.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.StoreSafeSeed.SignatureValidity"
    enum="VariationSeedSignature" expires_after="2022-06-14">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of verifying the safe variations seed's signature. Recorded when
    attempting to store the safe seed on disk.

    Expired after M77 and revived in M93.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.Streak.Crashes" units="crashes"
    expires_after="2022-05-09">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The number of consecutive crashes observed by the VariationsService without
    a single intervening successful seed fetch. Recorded during Chrome startup
    when the MetricsStateManager's CleanExitBeacon is created.

    Prior to M92, this was recorded when the SafeSeedManager was created.
  </summary>
</histogram>

<histogram name="Variations.SafeMode.Streak.FetchFailures" units="failures"
    expires_after="2022-05-09">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The number of consecutive failed attempts to fetch a new seed by the
    VariationsService. Recorded during Chrome startup when the SafeSeedManager
    is created.
  </summary>
</histogram>

<histogram name="Variations.SafeModeCachedFlags.Streak.Crashes" units="crashes"
    expires_after="2022-06-21">
  <owner>hnakashima@chromium.org</owner>
  <owner>src/chrome/browser/flags/OWNERS</owner>
  <summary>
    The number of consecutive crashes observed by Android's CachedFeatureFlags
    without a single intervening successful flag cache from native. Recorded the
    first time a cached flag is checked.

    Android only.
  </summary>
</histogram>

<histogram name="Variations.SafeModeCachedFlags.{Event}"
    enum="VariationsSafeModeCachedFlagsBehavior" expires_after="2022-06-21">
  <owner>hnakashima@chromium.org</owner>
  <owner>src/chrome/browser/flags/OWNERS</owner>
  <summary>
    What behavior of Safe Mode for CachedFlags (including not engaging it) was
    performed.

    {Event}

    The ratio &quot;Cached&quot; / (&quot;WillCache&quot; - &quot;Pause&quot;)
    is the success rate for a given mode, and (100% - success rate) is the crash
    rate.

    Android only.
  </summary>
  <token key="Event">
    <variant name="Cached"
        summary="&quot;Cached&quot; is recorded at the point where flags were
                 cached from native to Shared Preferences."/>
    <variant name="Engaged"
        summary="&quot;Engaged&quot; is recorded at the point where whether
                 to engage safe mode is decided."/>
    <variant name="Pause"
        summary="&quot;Pause&quot; is recorded when the initialization flow
                 is aborted."/>
    <variant name="WillCache"
        summary="&quot;WillCache&quot; is recorded when the initialization
                 flow that should result in caching flags is entered."/>
  </token>
</histogram>

<histogram name="Variations.SeedDateChange" enum="VariationsSeedDateChange"
    expires_after="2022-06-14">
  <owner>jwd@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Counts if a response from the variations server is the first response of the
    day or not. This is counted when a new valid seed or a 304 is received. The
    date line is computed in UTC and the times being compared are the server
    time from the server response and the stored server time from the last
    successful request.
  </summary>
</histogram>

<histogram name="Variations.SeedFetchResponseOrErrorCode{ConnectionType}"
    enum="CombinedHttpResponseAndNetErrorCode" expires_after="2022-06-14">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    HTTP response codes and network error encountered by VariationsService when
    attempting to fetch a variations seed from the server over an
    {ConnectionType} connection.
  </summary>
  <token key="ConnectionType">
    <variant name="" summary="HTTPS"/>
    <variant name=".HTTP" summary="HTTP"/>
  </token>
</histogram>

<histogram name="Variations.SeedFreshness" units="minutes"
    expires_after="2022-07-03">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The time interval between when the variations seed was downloaded and when
    it was loaded for use.

    Recorded after the seed is loaded for both regular seeds and safe seeds. Not
    recorded for expired seeds or for seeds with an unknown download time, which
    is typically a seed imported via first run. A seed that (a) was fetched over
    30 days ago and (b) is older than the binary build time is considered
    expired.

    Prior to M93, this metric was recorded under slightly different conditions.
    First, the metric was recorded for safe seeds--expired or not--as long as
    they had download times. As of M93, it's no longer recorded for expired safe
    seeds. Second, the metric was not previously recorded for regular seeds that
    were older than 30 days, but as of M93, the freshness is recorded for seeds
    that are older than 30 days and newer than the binary build time.

    Prior to M99, this histogram would not be logged for first run seeds (where
    they were not fetched by Chrome, but provided externally, such as part of
    Chrome installation via Google Update). In M99+, this histogram will be
    logged with a value of 0 minutes, so that the seed is considered fresh.
  </summary>
</histogram>

<histogram name="Variations.SeedLoadBlockingTime" units="ms"
    expires_after="2022-12-13">
  <owner>ntfschr@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    Records the time spent blocking WebView startup to wait for the variations
    seed. This is less than the entire time needed to load the seed, since
    startup is only blocked if loading is not complete by the time the seed is
    needed. This would ideally have a maximum value equal to the timeout in
    VariationsSeedLoader, but there is no actual limit on how late that timeout
    could fire. This is logged once per WebView startup, whether or not loading
    the seed was successful.
  </summary>
</histogram>

<histogram name="Variations.SeedLoadResult" enum="VariationsSeedLoadResult"
    expires_after="2022-07-03">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records whether the latest variations seed was successfully read from local
    state on startup. Records a detailed reason on read failure. Not recorded
    when running in safe mode.
  </summary>
</histogram>

<histogram name="Variations.SeedProcessingTime" units="ms"
    expires_after="2022-11-20">
  <owner>isherman@chromium.org</owner>
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records how long it takes to load and apply a variations seed. Recorded only
    when the seed is successfully loaded and applied. To help diagnose a
    processing time increase, see whether Variations.AppliedSeed.DataSize and
    Variations.AppliedSeed.StudyCount increased at the same time.
  </summary>
</histogram>

<histogram name="Variations.SeedStoreResult" enum="VariationsSeedStoreResult"
    expires_after="2022-06-14">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the result of storing the variations seed that was received from the
    server. Also logs the types of data received (gzip, delta, etc).
  </summary>
</histogram>

<histogram name="Variations.SeedUsage" enum="VariationsSeedUsage"
    expires_after="2022-06-14">
  <owner>caitlinfischer@google.com</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Captures details about Chrome's attempt to use a VariationsSeed, e.g.
    whether Chrome used a safe seed. Recorded once during Chrome startup after
    attempting to load a seed and before field trials are created.
  </summary>
</histogram>

<histogram name="Variations.SimulateSeed.Duration" units="ms"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the time taken to perform variations seed simulation.

    Recorded on every variation seed simulation, which follows a fetch.
  </summary>
</histogram>

<histogram name="Variations.SimulateSeed.KillBestEffortChanges" units="units"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the result of variations seed simulation. Logs the number of
    experiment groups in the &quot;kill best effort&quot; category that are
    expected to change on a restart of the browser with the received seed.

    Recorded on every variation seed simulation, which follows a fetch.
  </summary>
</histogram>

<histogram name="Variations.SimulateSeed.KillCriticalChanges" units="units"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the result of variations seed simulation. Logs the number of
    experiment groups in the &quot;kill critical&quot; category that are
    expected to change on a restart of the browser with the received seed.

    Recorded on every variation seed simulation, which follows a fetch.
  </summary>
</histogram>

<histogram name="Variations.SimulateSeed.NormalChanges" units="units"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the result of variations seed simulation. Logs the number of
    experiment groups in the &quot;normal&quot; category that are expected to
    change on a restart of the browser with the received seed.

    Recorded on every variation seed simulation, which follows a fetch.
  </summary>
</histogram>

<histogram name="Variations.StoreSeed.DataSize" units="KiB"
    expires_after="2022-06-14">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The size of the variations seed data, which may be a partial (delta) or
    compressed (gzip) payload, see Variations.SeedStoreResult.
  </summary>
</histogram>

<histogram name="Variations.StoreSeedSignature" enum="VariationSeedSignature"
    expires_after="2022-04-22">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The result of verifying the variations seed signature, recorded when the
    variations seed is stored to Local State after being retrieved from the
    server.
  </summary>
</histogram>

<histogram name="Variations.StringsOverridden" units="strings"
    expires_after="2018-08-30">
  <owner>asvitkine@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Records the number of UI strings overriden for each study that overrides
    strings. Recorded at start up when each study is evaluated.
  </summary>
</histogram>

<histogram name="Variations.TimeSinceLastFetchAttempt" units="minutes"
    expires_after="2022-04-22">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    The time since the previous attempt to fetch the variations seed within the
    same session, with 0 indicating that this is the first attempt. Recorded
    when a variations seed fetch is attempted by the VariationsService.
  </summary>
</histogram>

<histogram name="Variations.UserChannel" enum="UserChannels"
    expires_after="2022-07-03">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Log the user channel assigned at browser startup used for evaluating the
    variations seeds.
  </summary>
</histogram>

<histogram name="Variations.WebViewDownloadJobFetchResult"
    enum="VariationsSeedFetchResult" expires_after="2021-01-31">
  <obsolete>
    Removed from code January 2021.
  </obsolete>
  <owner>rmcelrath@chromium.org</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    The result of a WebView seed download. Records both the HTTP code and
    various error values in one enumeration.
  </summary>
</histogram>

<histogram name="Variations.WebViewDownloadJobFetchTime2" units="ms"
    expires_after="2021-01-31">
  <obsolete>
    Removed from code January 2021.
  </obsolete>
  <owner>rmcelrath@chromium.org</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    The duration of the network request to downloads a new WebView variations
    seed from the variations server to the central on-device service.
  </summary>
</histogram>

<histogram name="Variations.WebViewDownloadJobInterval" units="minutes"
    expires_after="2022-12-13">
  <owner>ntfschr@chromium.org</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    The time between the start of two consecutive WebView seed downloads by
    WebView's service. This metric will not be written if seeds are never
    downloaded.
  </summary>
</histogram>

<histogram name="Variations.WebViewDownloadJobQueueTime" units="minutes"
    expires_after="2022-12-13">
  <owner>ntfschr@chromium.org</owner>
  <owner>src/android_webview/OWNERS</owner>
  <summary>
    The delay between when a WebView seed download was scheduled by the service
    with the JobScheduler and when it was executed.
  </summary>
</histogram>

<histogram name="Variations.{Mode}CreateTrials.SeedExpiry"
    enum="VariationsSeedExpiry" expires_after="2022-04-22">
  <owner>asvitkine@chromium.org</owner>
  <owner>rkaplow@chromium.org</owner>
  <owner>src/base/metrics/OWNERS</owner>
  <summary>
    Stores the state of the loaded variations seed, e.g. not expired. Recorded
    after the seed is loaded and before trials are created from the seed. Note
    that seeds for which this metric is recorded may not be applied, e.g. when
    the seed has expired.

    {Mode}
  </summary>
  <token key="Mode">
    <variant name=""
        summary="Recorded for all successfully loaded seeds. Not recorded in
                 variations safe mode. Note that the concept of an expired
                 seed changed in M93. Prior to M93, expired seeds were those
                 that were more than 30 days old. As of M93, seeds that are
                 older than 30 days and older than the binary's build time
                 are considered expired."/>
    <variant name="SafeMode."
        summary="Recorded for safe seeds when Chrome attempts to run in
                 variations safe mode. This metric was added in M93."/>
  </token>
</histogram>

</histograms>

</histogram-configuration>